## https://yukicoder.me/problems/no/1831

from collections import deque

def main():
    N = int(input())

    matrixs = [[-1] * (N - 1) for _ in range(2 * N - 1)]
    queue = deque()
    for n in reversed(range(1, 2 * N)):
        for _ in range(n):
            queue.append(n)
    
    for j in range(N - 1):
        for i in range(2 * N - 1):
            matrixs[i][j] = queue.popleft()
    
    a_map = []
    prev_value_tuple = None
    for i in range(2 * N - 1):
        value_tuple = tuple(matrixs[i])
        if prev_value_tuple != value_tuple:
            a_map.append([value_tuple, 1])
        else:
            a_map[-1][1] += 1
        prev_value_tuple = value_tuple
    
    answers = []
    for value_tuple, cnt in a_map:

        v_map = {}
        reserve_queue = deque()
        while len(queue) > 0 and cnt > 0:
            v = queue.popleft()
            if v not in v_map:
                v_map[v] = 0

            if v_map[v] < 2:
                v_map[v] += 1
                cnt -= 1
            else:
                reserve_queue.append(v)
        
        if cnt > 0:
            print("No")
            return
        
        while len(reserve_queue) > 0:
            w = reserve_queue.pop()
            queue.appendleft(w)
        
        for v, cnt2 in v_map.items():
            for _ in range(cnt2):
                t = list(value_tuple)
                t.append(v)
                answers.append(t)
    
    print(len(answers))
    for tuples in answers:
        print(" ".join(map(str, tuples)))





    


        

    



if __name__ == "__main__":
    main()